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A117054 Number of ordered ways of writing n = i + j, where i is a prime and j is of the form k*(k+1), k > 0. 2
0, 0, 0, 1, 1, 0, 1, 1, 2, 0, 1, 0, 2, 1, 2, 0, 2, 0, 3, 0, 1, 1, 3, 0, 4, 0, 1, 0, 2, 0, 3, 1, 3, 0, 3, 0, 3, 0, 2, 0, 2, 0, 5, 1, 2, 0, 3, 0, 6, 0, 1, 0, 4, 0, 3, 0, 1, 1, 5, 0, 5, 0, 3, 0, 3, 0, 4, 0, 2, 0, 3, 0, 7, 1, 3, 0, 3, 0, 6, 0, 2, 0, 4, 0, 6, 0, 2, 0, 4, 0, 5, 1, 3, 0, 5, 0, 3, 0, 3, 0, 5, 0, 8, 0, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,9

COMMENTS

Based on a posting by Zhi-Wei Sun to the Number Theory Mailing List, Mar 23 2008, where he conjectures that a(2n+1) > 0 for n >= 2.

Zhi-Wei Sun has offered a monetary reward for settling this conjecture.

No counter-example below 10^10 (D. S. McNeil).

LINKS

Table of n, a(n) for n=0..104.

Zhi-Wei Sun, Posing to Number Theory List (1)

Zhi-Wei Sun, Posting to Number Theory List (2)

Zhi-Wei Sun, Conjectures on sums of primes and triangular numbers, arxiv:0803.3737 and Journal of Combinatorics and Number Theory, 1 (2009), no.1, 65-76

MAPLE

t0:=array(0..300); for n from 0 to 300 do t0[n]:=0; od:

t1:=[seq(ithprime(i), i=1..70)]; t2:=[seq(n*(n+1), n=1..30)];

for i from 1 to 70 do for j from 1 to 30 do k:=t1[i]+t2[j]; if k <= 300 then t0[k]:=t0[k]+1; fi; od: od:

t3:=[seq(t0[n], n=1..300)];

CROSSREFS

Cf. A132399, A144590.

Sequence in context: A089650 A085513 A259965 * A036579 A139353 A029397

Adjacent sequences:  A117051 A117052 A117053 * A117055 A117056 A117057

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, Jan 15 2009

STATUS

approved

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Last modified November 12 04:21 EST 2019. Contains 329051 sequences. (Running on oeis4.)